Statistical Investigation on the Temperature Actions of CFST Truss Based on Long-Term Measurement

Concrete-filled steel tube (CFST) trusses are the most common elements used in long-span CFST bridges; however, the temperature actions have not been systematically investigated. This paper presents a long-term temperature measurement on a CFST truss segment and decompose its temperature actions into uniform temperature, vertical temperature difference (VTD) between upper and lower chords, and lateral temperature difference (LTD) between left and right chords. Based on the recorded long-term meteorological data, empirical formulae were established to predict these temperature actions and prove with a high degree of confidence. Subsequently, an effective extreme value analysis (EVA) based on the Monte Carlo method was presented to calculate the representative values of these temperature actions. All these values are greater than the recommended values in the Chinese Code Specification. Based on a series of frequency analysis on each temperature action, three potential combinations were finally determined. The combinations were all input into a frame finite-element model of a 220 m span CFST arch bridge for the thermal response calculation and comparisons with the Specification temperature actions and dead load. These efforts suggest that the investigative methodology and the proposed temperature action combinations can expand the provisions of the Chinese Code Specification and are more suitable for the thermal response calculation and design of CFST arch bridges with a truss arch rib.